Hydraulic dredging apparatus



C. K. LITTLE HYDRAULIC DREDGING APPARATUS June 27, 1944.

Filed June 23, 1943 2 Sheets-Sheet 1 (L/ITZZIZZZe.

June 27, 1944.

C. K. LITTLE HYDRAULIC DREDGING APPARATUS 2 SheetsSheet 2 Filed June 23,1943 gwuwm Cfjfllz'iile. (SW MAW Momma Patented June 27, 1944 UNITEDSTATES I PATENT OFFICE HYDRAULIC DREDGING APPARATUS Charles K. Little,Vicksburg, Miss.

Application June 23, 1943, Serial No. 491,993

4 Claims.

My invention relates to hydraulic dredging apparatus.

An important object of the invention is to provide apparatus of theabove mentioned character including a rotary cutter which not onlyloosens the solid material to be dredged, but serves to aid in loadingthe same into the intake of a centrifugal dredging pump, in addition tothe suction loading action of such pump, which is limited to atmosphericpressure.

A further object of the invention is to provide apparatus of the abovementioned character including a rotary cutter, to be used with theconventional centrifugal dredging pump, and which may also be usedWithout the centrifugal dredging pump, to loosen the material, and feedthe same through the pipe line.

A further object of the invention is to provide a hood for coaction withthe improved rotary cutter, for aiding in the loading of the water andsolid material in suspension therein to the cen trifugal dredging pump,and which. hood will also increase the efficiency of the apparatus, whenthe conventional open rotary cutter is substituted for my improvedrotary cutter and used in connection with the hood.

A further object of the invention is to provide a device of the abovementioned character which will act as a low pressure pump and havingblades or vanes which will cut and loosen the solid material.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a side elevation of a combined rotary cutter and lowpres-sure pump embodying my invention, parts broken away,

Figure 2 is a plan view of the same,

Figure 3 is a longitudinal section taken on line 3-3 of Figure 4,

Figure 4 is a transverse section taken on line 4-4 of Figure 3, Figure 5is a perspective view of the hood and associated elements, partly insection, with the rotary cutter removed,

Figure 5 is a diagrammatic view of the volute passage, showing itsgradual increase in depth,

Figure 6 is a rear end elevation of the rotary cutter,

Figure 7 is a front end elevation of the same, and

Figure 8 is a partly diagrammatic view of the assembled centrifugaldredging pump and the combined low pressure pump and rotary cutter.

In the drawings, wherein forthe purpose of illustration is shown apreferred embodiment of my invention, the numeral I!) designates aladder or support, which is hinged at on end to the dredge vessel, to beswung in a vertical plane so that its free end may be raised andlowered.

Arranged at the free end of the ladder Ill is a combined low pressurepump and rotary cutter including a cylindrical hood or housing I I,rigidly attached to the latter by any suitable means. This hood has itsfront end open while its rear end is covered by a head l2. The head l2includes a central hub l3, integral with the head l2, and having aradial stationary abutment M, in the plane of the face of the hub. Thehead I2 is formed or shaped to provide a volute or spiral passage l5,starting at l6, upon one side of the stationary abutment I4 andextending circumferentially of the hood ll interiorly of the same. Thepassage I5 is between the periphery of the hood H and the hub. Theintake end of the volute passage l5 starts at 16, as stated, and thepassage gradually increases in depth until its outlet end is reached.This is indicated by the transverse curved lines in Figure 5 which is adiagrammatic view of the passage. The passage l5 extends beyond theopposite side I! of the stationary abutment. The outlet end of thevolute passage l5 extends behind the abutment and is continued in theform of a tubular extension l8, integral with the hood, and this tubularextension is connected with a suction pipe 19, which leads to the intakeside of a conventional centrifugal dredge pump l9, mounted upon thevessel. The pipe l9 has a flexible joint 20' so that it will notinterfere with the manipulation of the ladder.

The hub I3 is provided with a bearing 20, receiving a rotary shaft 2|,driven by any suitable means. Mounted upon this rotary shaft to turntherewith is a rotary cutter 22. This rotary cutter includes a solid orclosed hub 23, having a flat rear end 24, operating in contact with orin close relation to the face of the hub I3 and the abutment M, asshown. This hub 23 may taper forwardly. Formed integral with the hub areimperforate blades or vanes 25, extending longitudinally thereof. Theseblades or vanes start at the hub and extend continuously radiallyoutwardly to their outer or cutting edges. These blades or vanes arevolute or spirallongitudinally with respect to the axis of the rotationof the hub. The blades or vanes 25 are disposed generally radially andare curved in cross section, and all blades or vanes face in the samedirection, which is the direction of rotation of the hub. These bladesor vanes also radially taper toward their forward ends. These blades orvanes form separate volute passages 25' between the blades, whichgradually increase in depth toward their rear ends, Figure 6. The vaneshave their rear ends circumferentially spaced, Figure 6, while theforward ends of the blades or vanes circumferentially overlap, Figure 7.The rear end of the hub 23 and the rear ends of the blades or vanes 25extend into the cylindrical hood or housing H, with a slight radialclearance between the blades or vanes and the hood II.

The operation of the apparatus is as follows:

The suction pipe I9 is connected with the suction side of thecentrifugal dredging pump l9 upon the dredge vessel, and th usualsuction is created in the pipe, to load the water and solid.

material in suspension therein, into the centrifugal dredging pump. Thissuction action is limited to atmospheric pressure. The ladder ii! ismanipulated to bring the rotary cutter 22 into engagement with the solidmaterial to be loosened. The cutter 22 is rotated clockwise, Figures 1,2, 3, 4 and '7. The blades or vanes 25 have their outer longitudinalcutting edges brought into engagement with the solid material and cut orloosen the same. The water and loosened solid material in suspensiontherein enters the passages 25 between the blades or vanes 25 and rtates with the blades or vanes and also travels axially with relation tothe blades or vanes toward their rear ends. The water and solid materialin suspension therein now enters the volute passa e l5 and will impingeagainst the wall of this passage due to the axial movement of the same.This axial movement of the water and solid material in suspensiontherein will cause the same to travel circumferentially within-thevolute passage l5 from the intake end thereof to its outlet end. Thiscircumferential travel within the passage I5 is also caused by therotation of the water and solid material in suspension therein with therotary cutter, and also to the action of centrifugal force upon thesame. The pump produced by the rotary cutter 22 and hood II is a lowpressure combination centrifugal, screw, and axial flow pump. It is thusseen that the rotary cutter 22 and hood I I serve as a low pressure pumpto force or feed the water and solid material suspended therein into thepipe l9 and serves to aid in loading the same ito the intake of thecentrifugal dredging pump, in addition to the suction loading action ofthe centrifugal dredging pump. It is preferred to drive the rotarycutter at about 40 to 60 R. P. M., when it is used in connection withthe centrifugal dredging pump.

In the event that extremely hard digging should be encountered, such asrock, I contemplate removing my improved rotary cutter and substitutingtherefor the conventional open rotary cutter employed for this work.When the conventional rotary cutter is used with my hood I l the volutepassage l5 would then reduce entrance losses, to some degree.

While I prefer using my hood and rotary cutter as a low pressure pump inconnection with the centrifugal dredging pump, for aiding in loading thesame, yet I contemplate dispensing with the centrifugal dredging pump.When this is done, the rotary cutter would be driven at a high speed andwould be relied upon to force or feed the waterand solid materialsuspended therein through the pipe line.

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may be.resorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, what I claim is:

1. In hydraulic dredging apparatus, a low pressure combined pump androtary cutter to aid in loading water and solid material. in suspensiontherein to the intake of a centrifugal dredging pump in addition to thesuction loading action of the centrifugal dredging pump, said lowpressure combined pump and rotary cutter including a rotary cutterelement to loosen the solid material and feed the water and solidmaterial in suspension therein axially of the rotary cutter element, anda part having a spiral passage to receive the water and solid materialin suspension therein from the rotary cutter element.

2. In hydraulic dredging apparatus, a low pressure combined pump androtary cutter to aid in loading water and solid material in suspensiontherein to the intake of a centrifugal dredging pump in addition to thesuction loading action of the centrifugal dredging pump, said lowpressure combined pump and rotary cutter including a rotary cutterelement having a closed hub and spiral blades carried by the hub andextending generally radially continuously from the hub to their outeredges and providing spiral passages between the blades, the bladesserving to loosen the solid material, and means forming a spiral passageto receive the water and solid material in suspension therein from therotary cutter element.

3. In hydraulic dredging apparatus, a hood having an end provided with aspiral passage in communication with the intake of a centrifu galdredging pump, and a rotary cutter having one end operating within thehood near the spiral passage, the rotary cutter including a closed huband generally radial volute imperforate blades, said blades beingcircumferentially spaced to form separate passages between them, thehood and rotary cutter serving as a low pressure pump to aid in loadingwater and solid material in suspension therein to the intake of thecentrifugal dredging pump in addition to the suction loading action ofthe centrifugal dredging pump, and means to drive the rotary cutter.

4. In hydraulic dredging apparatus, a hood having its forward end openand including a head covering its rear end, said head having an abutmentand a spiral passage, said volute passage starting upon one side of theabutment and extending substantially to the opposite side of theabutment, a pipe connected with the outlet end of the spiral passageand. having connection with the intake of a centrifugal dredging pump,and a rotary cutter associated with the hood, said rotary cutterincluding a closed hub and generally radial blades carried by andextending longitudinally of the hub, said blades extending con tinuouslyfrom the hub to their outer edges to form separate passages, said bladesextending longitudinally of the hub and being spiral and transverselycurved, the blades extending into the hood and terminating in closerelation to the head, the hood and rotary cutter serving as a lowpressure pump to aid in loading the water and solid material insuspension therein to th intake of the centrifugal dredging pump inaddition to the suction loading action of the centrifugal dredging pump,and means to drive the rotary cutter.

CHARLES K, LITTLE.

